一.虚拟语气

　　虚拟语气表示说话人的主观愿望、猜疑、建议或与事实不符的假设等，而不表示客观存在的事实。虚拟语气是由句中的谓语动词的特殊形式表示出来的。

　　虚拟语气主要分为与现在事实相反，与过去事实相反以及与将来事实相反三个种类。让我们一一来看下它们的结构和用法吧!

　　1、表示与现在事实相反的情况

　　从句：If+主语+动词一般过去时(Be动词用were)

　　主句：主语+ should/would/might/could+do：

　　If I were you，I would take an umbrella.

　　如果我是你，我会带把伞。(事实：我不可能是你)

　　If I knew his telephone number，I would tell you.

　　如果我知道他的电话号码，我就会告诉你。(事实：不知道)

　　If there were no air or water，there would be no living things on the earth.

　　如果没有水和空气，地球上就不会有生物。(事实：地球上既有空气也有水)

　　If I had any money with me，I could lend you some.

　　如果我带钱了，我就会借给你些。(事实：没有带钱)

　　If he studied harder，he might pass the exam.

　　如果他再努力些，就能通过考试了。(事实：没有努力)

　　If I were you， I'd wear a shirt and tie.

　　如果我是你，我就会穿衬衫和领带。(事实：我并不是你)

　　2、表示与过去事实相反的情况

　　从句：If+主语+had+done

　　主句：主语+should/would/might/could+have done

　　eg：If I had got there earlier，I should/would have met her.

　　如果我早到那儿，我就会见到她。(事实：去晚了)

　　If he had taken my advice，he would not have made such a mistake.

　　如果他听我的劝告的话，就不会犯这样的错误了。

　　(事实：没有听我的话)

　　3、表示与将来事实相反

　　从句：①if+主语+were to do

　　②if+主语+should+do

　　③if+主语+动词一般过去式(be动词用were)

　　主句：主语+should/would/might/could+do

　　eg：If he should come here tomorrow，I would talk to him.

　　如果他明天来这儿的话，我就跟他谈谈。(事实：来的可能性很小，不可能)

　　If there were a heavy snow next Sunday，we would go skating.

　　如果下周日下大雪，我们就去滑冰。(事实：下雪可能性很小，不可能)

　　If she were to be here next Monday，I would tell her about the matter.

　　如果她下周一来这儿的话，我就会告诉她这件事的始末。(事实：来的可能性很小，不可能)